Emoji: Move a comment to match the restructure in [31779], and add an extra comment explaining how emoji rendering support is detected.

See #31242


Built from https://develop.svn.wordpress.org/trunk@31788


git-svn-id: http://core.svn.wordpress.org/trunk@31768 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/wp-emoji.js

@@ -82,6 +82,11 @@
 				return false;
 			}
 
+			/*
+			 * Chrome on OS X added native emoji rendering in M41. Unfortunately,
+			 * it doesn't work when the font is bolder than 500 weight. So, we
+			 * check for bold rendering support to avoid invisible emoji in Chrome.
+			 */
 			context.textBaseline = 'top';
 			context.font = '600 32px Arial';
 
@@ -99,9 +104,9 @@
 				return canvas.toDataURL().length > 3000;
 			} else {
 				/*
-				 * Chrome on OS X added native emoji rendering in M41. Unfortunately,
-				 * it doesn't work when the font is bolder than 500 weight. So, we
-				 * check for bold rendering support to avoid invisible emoji in Chrome.
+				 * This creates a smiling emoji, and checks to see if there is any image data in the
+				 * center pixel. In browsers that don't support emoji, the character will be rendered
+				 * as an empty square, so the center pixel will be blank.
 				 */
 				context.fillText( String.fromCharCode( 55357, 56835 ), 0, 0 );
 				return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.2-beta1-31787';
+$wp_version = '4.2-beta1-31788';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.